An OLED display panel can emit light when it is driven by a current generated by a driving thin film transistor (TFT) in a saturated state. When an identical grayscale voltage is applied, different driving currents will be generated by different critical voltages, which thus results in inconsistency of the currents. For example, a traditional 2T1C-based pixel driving circuit is always of a less brightness evenness, and currently, such a solution is adopted so as to add a compensating circuit within a pixel, and eliminate an effect of a threshold voltage Vth of the driving TFT by the compensating circuit. However, usually an increase in the number of the TFTs will lead to a rapid decrease in an aperture ratio and an increase in the production cost. In the case of an identical pixel driving current, there exits not necessarily a decrease in the brightness of the OLED display panel with a low aperture ration, but a current density of an organic light-emitting layer will certainly increase, which will readily result in aging of a material of the light-emitting layer, and thereby result in a short service life of the entire OLED display panel.